An interesting blog post from a Microsoft Certified Master in SharePoint, Maxime Bombardier: "What SharePoint 2010 Looks Like With IE 6":
"80% of companies didn't upgrade from Windows XP yet and a good chunk of these didn't upgrade the browser. Also, upgrading from IE6 to IE7/8 may look easy to end users, and it is, [but] it may not be the case for companies who have 3rd party ActiveX components that do not work on IE7+ unless they also upgrade back-end systems that these ActiveX components talk to. This becomes a massive headache that companies are looking into, but it takes 1-3 years to upgrade it all. Collaboration tools such as SharePoint are relatively new for these companies, they have ad-hoc deployments but, often, they do not have an enterprise deployment yet. Deploying SharePoint 2010 is very compelling but the browser situation makes this difficult."
He goes on to say, in a followup post that could well have been titled "You Can Use IE 6 and SharePoint 2010, Though Microsoft Won't Support It and You Can't Blame Me If You Don't Like It" but is more quietly titled "What can work with Internet Explorer 6 and SharePoint 2010":
"This is not an official Microsoft response but rather a view at exploring options with IE6 and SharePoint 2010. Also, my personal opinion is that using IE6 with SharePoint 2010 should be a last resort after evaluating risks and concerns compared to a migration. But I’m also a consultant and have to look at all solutions to better guide customers effectively with their business in mind, not just wishful thinking that all companies can simply upgrade easily."
He has a nice table midway down the page with graphics showing what worked and what didn't when he tested SharePoint 2010 and IE 6.